Like the fantasy Master Maze series, the Sci-Fi line from Dwarven Forge is modular, comes pre-painted, is designed for use with 25mm minatures and has a 1" grid pattern built into all the floor designs.

From the publishers website:
This is a great first set for anyone wishing to explore our Sci-Fi line! It has enough pieces to make a room -- in 100's of possible combinations. This is a great gift for someone starting out with us, and collectors buy several of them to make huge set-ups for their Star Wars and Warhammer 40K games.